I keep an 80/20 mix of Coleman lantern fuel (naptha) to 20% plain paint thinner. The paint thinner is very slow and it reduces the flash-off time of the solution. Best solvent wash in my profession. But aside from that, it reduces the "astringent" or harsh action of pure naptha. Pure naptha is a bit harsh on the finished surfaces of the camera and lens. Further, since it is slow, you can clean gummy substances with less wiping (abrasion), and therefor better than pure lighter fluid for camera work, and especially lenses. You might prefer 85/15, but whatever. I have listened to all these folks using lighter fluid and never mentioned this concoction, but it really is better.
I use Coleman fuel in an ultrasonic to clean very gummy dirty things. Sometimes with a few drops of GUNK concentrate. Oddly, I never use it in my campstoves, it's far too expensive for that!